Heli-Coil Spark Plug Thread Repair Inserts

Heli-Coil Spark Plug Threaded Inserts

Repair stripped or damaged spark plug threads! Heli-Coil spark plug threaded inserts are manufactured from 18-8 round stainless steel wire formed into a 60 degree diamond-shaped wire. This cold-worked wire (which has a tensile strength of 200,000 psi) is wound into a helical coil with a driving tang and notch—to remove the tang after the insert is screwed into the Heli-Coil tapped hole. In their free state, the inserts are larger in diameter than the tapped hole. Once installed, each insert assumes the configuration of the tapped hole. The resulting outward spring-like action anchors the inserts in place. The Heli-Coil spark plug inserts become an integral part of the cylinder head, providing high-strength threads which exceed in surface smoothness, hardness, and accuracy than any other threads.

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